Ebola virus vaccines - reality or fiction?

Abstract

For 40 years ebolaviruses have been responsible for sporadic outbreaks of severe and often fatal hemorrhagic fever in humans and nonhuman primates. In December 2013 an unprecedented Zaire ebolavirus epidemic began in West Africa. Although "patient zero" has finally been reached after 2 years, the virus is again causing disease in the region. Currently there are no licensed vaccines or therapeutic countermeasures against ebolaviruses; however, the epidemic in West Africa has focused attention on the potential vaccine platforms developed over the past 15 years. There has been remarkable progress using a variety of platforms including DNA, subunit, and several viral vector approaches, replicating and non-replicating, which have shown varying degrees of protective efficacy in the "gold-standard" nonhuman primate models for Ebolavirus infections. A number of these vaccine platforms have moved into clinical trials over the past year with the hope of finding an efficacious vaccine to prevent future outbreaks/epidemics of Ebola hemorrhagic fever on the scale of the West African epidemic.

Keywords: Ebolavirus; animal model; filovirus; prophylaxis; vaccine.

Fig. 1. Overview of vaccine approaches successfully tested in EBOV animal disease models (rodents and macaques) and currently in human clinical trials

Fig. 2. Distribution of ongoing phase I–III clinical trials in the world

Immunization with Human Adenovirus (HuAd) or Chimpanzee Adenovirus (ChAd) alone or in combination with Modified Vaccinia Ankara (MAV); DNA vaccination; recombinant Vesicular stomatitis virus (rVSV-ZEBOV); recombinant ZEBOV glycoprotein (ZEBOV-GP). Sources: www.ClinicalTrials.gov; www.pactr.org